This type of system could be great in all honesty. People have been asking for a dueling system (Not open world PvP) and myself as an RP'er would love to see this implemented.

Just don't allow duels in Cities and towns and only allow them in open spaces in the world. Also make it so a few meters from the city is a no Dueling zone, that way people aren't zoning out of a city into the middle of a duel. There could also be certain areas in cities set aside for duels like the Ul'dah coliseum could open up as a duel only area inside the city which can be reserved for private duels. Say, make it an instanced area where you can have a 1 on 1 up to an 8 on 8.

Just make it to where we can automatically decline duels if we don't feel up to it and all will be well.